The experiments of this series formed a preliminary study for the purpose of testing the effect of moderate doses. One decigram of caffein per kilo was given daily for several days; when administered at longer intervals the dose was increased to 150 to 200 mg per kilo. It was found that the smaller doses did not produce any symptoms; even the weights of the animals were not influenced. Doses of medium size given on two successive days were likewise without any noticeable effect (Nos. 182, 183, 123, 101). When a third dose of this size was given within 48 or 24 hours it proved fatal (Nos. 123, 182, and 183). Exceptionally, however, moderately large doses (for rabbits) may be given for three consecutive days without fatal issue, as in rabbit No. 101. When given at intervals of two to three days, larger doses, as may be seen from the protocols, can be administered without causing acute death (Nos. 173, 181, 201). The results of the tests of this series point to the absence of any accumulation and to the possible elimination of moderate doses of caffein and its products of decomposition within 24 hours or thereabouts. When the doses are larger the time of its elimination is apparently longer, as shown by the fact that repetitions of the dose the next day may be fatal, but when a longer interval is allowed it may be given without causing death. It will be observed that only one rabbit of this series survived, but it was extremely emaciated. This condition has been observed in a number of cases after caffein had been given for several days. Even when the drug was withdrawn the animals continued to lose weight. This may be explained by the condition of the gastro-intestinal canal as found at autopsy. The presence of inflammation of the mucous membrane of the stomach and intestines, with ulceration of the mucous membrane of the pylorus in one of the rabbits (No. 173) of the series, in all probability caused diminution or loss of appetite, which of itself would tend to cause loss of flesh and strength and finally death. Protocols of the experiments follow. _Rabbit 173._ _Carrots were fed from October 1 to 18 and oats for the remainder of the experiment._ ---------+---------+--------- Date. | Weight. | Caffein | |per kilo. ---------+---------+--------- | _Grams._| _Gram._ Oct. 9 | 1,980 | 0.141 Oct. 11 | 1,905 | .190 Oct. 13 | 1,930 | .207 Oct. 16 | 2,005 | 0.220 Oct. 18 | 1,845 | Oct. 20 | 1,740 | .230 ---------+---------+-------- October 21: Paralysis of posterior extremities. October 22: 9 a. m., found dead.